This invention relates broadly to apparatus for contacting large surfaces of a liquid, such as water, with a gas, such as air, for the purpose of humidifying air. More particularly, it refers to an improved means for the uniform distribution of water to an evaporative element in such an apparatus.
The humidification of dry air normally occurring in buildings during the winter heating season by the evaporation of water therein, depends upon the efficient evaporation of water from the continuously wetted surfaces of an evaporative element or pad as, for example, an interstitial body having extensive surfaces to provide a large area of contact of the air with water. The air to be humidified is forced through the openings of the element where it contacts the wet baffles or fibers of which the evaporative element is composed. Exposure of relatively large water surfaces in this way results in the evaporation of large amounts of the water.
An example of this type of evaporating apparatus is disclosed in the assignee""s U.S. Pat. No. 5,211,891 issued May 18, 1993. In this apparatus, the humidifier includes a base portion and a removable cover. An evaporative pad or water panel is removably disposed within the base. A water feed tube is connected to a solenoid valve equipped with a small orifice for controlling the flow of water therethrough and supplies water to a trough-like distribution tray. The water flows by gravity from the distribution tray through openings and down through the water panel. Air is forced through the water panel and the air evaporates water on the water panel and humidified air is delivered to the house, building or heated space. The evaporative water panel is held within a frame mounted in the base portion in order to reduce the air bypass around the water panel, and to contain mineral deposits that build up on the water panel as a result of the evaporative process.
A typical prior art distribution tray is a plastic reservoir 0.875 inches deep which spans the top of a water panel. Within the reservoir are six cylindrical towers with V-shaped metering weirs intended to evenly spread the water to six places on the top of the water panel. The interior of this distribution tray is coated with a spray adhesive and pumice powder in the hopes of improving the evenness of the water metering. This pumice coating process is a very undesirable manufacturing step. It is labor intensive, messy and very hard toontrol, so that the coating evenly cogs all parts. When the coating is not uniform, the metering rate of individual weirs is not equal. By design, the distribution tray must be relatively large to contain an adequate water level for the metering weirs to function. This directly effects the cost of the part and indirectly the cost of the humidifier as a whole since the humidifier must be sized to contain the distribution tray. This larger size effects versatility in installation of the humidifier, since more space is required.
Another critical problem arises during installation. Weir-type metering systems are very sensitive to being mounted level. That is, the plane of the upper surface of the distribution tray should be parallel to the earth""s horizon. If mounted at an angle, water will be deeper at one weir than the others and water flow will be uneven. In some cases, all the water may flow out only the lowest weir. Non-uniform shape of the individual metering weirs is another major problem. In manufacture, the weir is effected by molding flash, trimming of flash, warpage of plastic, and uneven coating of pumice. In actual use, mineral deposits may change the shape, cleaning can scrape away some of the pumice coating, or the pumice coating erodes away in some water conditions. When the metering weir is not uniform, water is not evenly distributed to the water panel. Another problem with the prior art distribution tray is its slow response time. When the humidifier turns on, it takes about 30 seconds for enough water to fill the distribution tray for the metering weir to begin supplying water to the water panel. Yet another problem is that the metering forces of a weir design are very low and easily disturbed to cause uneven flow. The operating pressure from the reservoir water level is only about 0.014 psi when all six weirs are functioning. This low pressure is within a realm of molecular water forces such as surface tension and capillary force. The metering rate is thus easily disturbed. When one weir does not start or stops flowing, the reservoir water level rises slightly and flow diverts to the remaining weirs. The pressure increase on the blocked weir is only about 10%, so there is very little force increase to encourage the weir to restart. Even if all but one weir is blocked, the pressure increases to only about 0.033 psi, still not enough to encourage blocked weirs to restart.
All of the above problems degrade the performance of humidifiers. Evaporation from the humidifier water panel is best when it is evenly covered with an adequate supply of water. Uneven distribution of water can lead to loss of wetted surface in the water panel and reduced evaporation.
Most competitor humidifiers are using variations of the weir. Different weir shape, placement, and materials are used. Some use surface textures or die cut wicking materials in place of pumice coating. All of these have the same drawbacks as the systems described above. One design lets the water stream from a single nozzle drop onto a series of ribs which divide the flow and guide each resulting stream to an outlet hole. This method takes up about the same space and has part costs similar to the prior art system. It also has low control forces and flow might easily be made to distribute unevenly. Other competitors avoid the distribution system by dipping the evaporator media in a reservoir. Stationary versions rely on wicking ability of media. These are not currently used on furnaces and performance is weak unless a recirculating pump is added with a high flow rate distributor. Dynamic systems form evaporator media in a wheel or drum shape that rotates through a reservoir to wet out. These are undesirable due to mechanical complexity and added cost.
Accordingly, it is desirable to provide a water distributor for humidifiers or other similar evaporative apparatus which overcomes the numerous problems and drawbacks set forth above. It is also desirable to provide a humidifier which replaces the prior art distribution tray, and provides a better water distribution to the evaporative water panel.
It is one object of the present invention to provide a water distributor which eliminates the prior art trough-like distribution tray and pumice coating thereof.
It is also an object of the present invention to provide a water distributor which enables a consistent, even flow of water at a desired flow rate therethrough and a quicker response time in which water is delivered to the evaporative water panel.
It is a further object of the present invention to provide a water distributor which is capable of unplugging flow blockages caused by particles in the incoming water flow.
It is an additional object of the present invention to provide a water distributor employing tortuous flow channels designed for high flow resistance.
Another object of the present invention is to provide a water distributor which is improved in unit size, cost and manufacturability.
Yet a further object of the present invention is to provide a water distributor which is insensitive to unlevel mounting angles in the humidifier.
In one aspect of the invention, a water distributor provides a uniform supply of water at a desired flow rate to an evaporative panel held in a frame in an evaporative apparatus. The water distributor includes a base having a plurality of flow channels, each of the flow channels includes an inlet port for receiving water from a source, an outlet port for delivering water to the evaporative panel, and a tortuous path connecting the inlet port with the outlet port to provide high flow resistance, so as to facilitate the consistent and even flow of water through each of the outlet ports. The base is comprised of an elongated, planar manifold and an elongated planar cover interconnected thereto. The water inlet is in communication with the water source and a header structure is in communication with the water inlet in each of the inlet ports. Each flow channel is configured in the shape of a square or star-shaped wave. The base is attached to the evaporative apparatus such that the outlet ports are positioned over the evaporative panel. A solenoid valve is interconnected with a water inlet fitting and the water inlet. In several of the embodiments, the base is attached to bosses depending from the evaporative apparatus. In another embodiment, the base has tabs formed thereon and the frame is formed with slots for receiving the tabs such that the base is supported from the frame.
In another embodiment, the base is provided with a tubular inlet extending from the water inlet. In yet another embodiment, a solenoid valve and water inlet assembly is attached directly to the base in communication with the water inlet. Yet another embodiment discloses a base which is provided with a filter and includes a groove for receiving an O-ring positioned between the water inlet and the water inlet fitting.
In another aspect of the invention, a water distributor is adapted to feed water uniformly at a controlled flow rate to an evaporative panel located therebelow. The water distributor includes a manifold having a length, a width and a thickness, and a water inlet at one end thereof, header structure in communication with the water inlet and extending along the length of the manifold, and an array of flow channels. Each of the flow channels has an inlet port connected with the header, an outlet port for delivering water to the evaporative panel and a tortuous path interconnecting the inlet port and the outlet port. A cover is attachable to the manifold. With this construction, water is supplied to the water inlet, the header structure and each of the inlet ports, flows with high resistance through each of the tortuous paths, and is delivered with a consistent and even flow at a controlled flow rate dependent on water pressure to each of the outlet ports for deposition onto the evaporative panel. The manifold and the cover are formed from a plastic material. Preferably, the array of flow channels is a group of six flow channels. In one embodiment, the array of flow channels is aligned in parallel. In another embodiment the array of flow channels is arranged in alternating fashion with some of the flow channels on one side of a longitudinal axis, and the other of the flow channels on the opposite side of the longitudinal axis, each of the outlet ports extending vertically through the thickness of the manifold. In several of the embodiments, each of the outlet ports are located along a side edge of the manifold. In some cases, a throttle resistor structure interconnects the water inlet with the header structure to improve control of flow rate. It may be that the throttle structure may take the form of an orifice upstream from the water inlet. In at least one embodiment, the cover and manifold are provided with a cooperating locator pin and hole arrangement. Also in another embodiment, the cover is integrally formed with a solenoid valve body receiving a stack of solenoid components. The cover and stack of solenoid components are retained together to form an assembly. The flow channels may take the form of a square or star-shaped wave.
Various other features, objects, and advantages of the invention will be made apparent from the following description taken together with the drawings.